Drainage apparatus



Jan. 5, 1943. D. E. LARsoN DRAINAGE'APPARATUS 3 Sheets-Sheet 2 Filedl Jap. 22, 1942 jiji Jan- 5, 1943- v 5 D'. E. I @RsoN 21,307,324

DRAINAGE APPARQTUS Filed Jan. 22,*1'942 ,v s sheets-'shef s Patented Jan. 5, 1943 DRAINAGE APPARATUS Donald E. Larson, Chicago, Ill., assgnor to 'Chicago Bridge & Iron Company, a corporation of Illinois Application January 22, 1942,Se1ialsNo. 427,821

3 Claims.

This invention relates to improvements in drainage apparatus and more especially such apparatus for draining rain water .from a concave roof or a roof having .a concavity therein. The invention is applicable, for example, in connection with the drainage of concave roofs of oil storage tanks and the like.

Some storage tanks of this character are made with roofs that rise and fall with changes in internal pressure so that at .times the center-of the roof is in a lower position than the periphery, thus forming a concavity that collects rain water unless suitable drainage means is provided.

Heretofore difculty has been encountered in draining such concave roofs. It has been customary to provide a flexible drain pipe through the tank but this has proved objectionable because of the diculty in obtaining access thereto. There are also other objections to draining the water from the roof of a tank down through the tank.

Among the features of my invention is the provision of drainage apparatus that is entirely outside of the tank. I have here illustrated the invention in use on a cylindrical tank having a concave roof.

In general, my improved apparatus comprises a syphon drain pipe with its upper leg connected to the concavity in the roof to be drained and its lower leg leading to a point outside of the tank below the roof. I provide means exposed to falling rain adapted to direct rain water into the lower leg of the syphon to start the same. In a device of this kind the low point or sump may be a relatively great distance from the periphery of the roof which is usually the high point. Consequently, the upper leg of the syphon may be of considerable length. In a case of this kind, therefore, it may be necessary or advisable to provide a relatively great amount of water in the lower leg in order to insure starting of the syphon. Consequently, I provide means for temporarily retaining a predetermined minimum amount of water in the lower leg before starting the syphon and then discharging the same to start the sy phon. I accomplish this by yieldingly closing the lower leg with means adapted to be opened by a predetermined amount of water in the lower leg.

Other features and advantages of my invention will appear more fully as I proceed with my specication.

In those forms of device embodying the features of my invention illustrated in the accompanying drawings, Fig. 1 is a view in side elevaline .2 -of Fig. 1Figs. 3, '4, i5 and 6 fare diagrammatic vviews 4showing .the operation ,of the device, Fig. 'l is ya View similar to .Fig.,2 showing .a modiiie'd form, Fig. f8 isran -enlarged fragmentary View of the lower end of the lower leg of the syphon. and Fig. 9 .is an enlarged sectional `view .of the swivel joint in the outlet pipe.

. As vshown .in .the drawings, I0 indicates a c ylindrical tank .with .a concave A.roof I-I `having `a central sump I2. :I3 ,indicates in general the upper leg Yof a `sy-phon drain pipe .and III the lower leg thereof. The end .I3a .of `the upper leg I3 has its-end in thesump-I2.

tion, Fig. 2 is a view taken as indicated by the 55 .The lower .end of .the lower leg I4 is enlarged as indicated by I4a to provide a vacuum chamber. This is designed to give enough capacity to the lower end of the lower leg of the syphon so that after the syphon starts there will be enough discharge to completely ll the upper leg I3 and thus insure continuous operation of the syphon after the start until the roof is entirely drained.

The lower end of the vacuum chamber I4a is provided with a swivel discharge pipe I5 having an enlarged end I5a. This pipe is normally held in a substantially upright position as shown in Figs. 1 and 2 by the counter-Weight I6. It is swiveled to the outlet pipe I4b at the bottom of the gacuum chamber by the swivel joint II. See Fig.

The lower end of the vacuum chamber Ida is connected by the pipe I8 to a trough I9 attached to the wall of the tank on the outside at a level somewhat above the top of the vacuum chamber I4a. This trough should be long enough so that whenever a rain starts it will quickly collect enough water to substantially ll the vacuum chamber IIIa. I have here shown this trough as extending entirely around the tank III.

Rain water runningdown the shell I0 is caught in the trough I9 and then flows into the vacuum chamber Ida. As the vacuum chamber becomes almost full, the weight of water in the enlarged end I5a of the swivel discharge pipe causes it to descend as shown by the arrows in Figs. 4 and 5. When it is down as shown in Figs. 5 and 6, water flows out of the discharge spout I5b thus draining the vacuum chamber IIa and starting the syphon. Flow through the syphon continues until the roof is drained. As the enlarged end I5a of the discharge pipe becomes nearly empty as shown in Fig. 6, the weight of the counterweight I6 causes it to rise to an upright position as indicated by the arrow in Fig. 6, the discharge pipe normally reymaining in an upright position as shown in Fig.

3 until the next rain fall.

Instead of providing a trough l 9 on the shell of the tank on the outside, I may provide a trough at the periphery of the roof as shown in Fig. 7, by sloping the outer margin of the roof downwardly slightly as indicated by Illa and providing a periphery flange H9. The trough thus formed is connected to the vacuum chamber I Ma by the pipe H8 which corresponds to the pipe I8 in the other figures. In other respects the general construction and operation of the device of Fig. 7 is the same as that 0f Figs. 1 and 2, the swivel discharge pipe H with its enlarged end H5a and its counterweight H5 corresponding to parts l5, |511 and I6, respectively, of the device of Figs. 1 and 2.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims, in which it is my intention to claim all novelty inherent in my invention as broadly as permissible, in view of the prior art.

What I claim as new, and desire to secure by Letters Patent, is:

1. Drainage apparatus for a, concave roof, including: a syphon drain pipe with its upper leg connected to the concavity in th'e roof to be drained and its lower leg leading to a point below the roof; means exposed to falling rain adapted to direct rain Water into the lower leg of the syphon to start the same; and means for yieldingly closing the lower leg, said means adapted to be opened by a predetermined minimum amount of water in the lower leg.

2. Drainage apparatus for a concave roof, including: a syphon drain pipe with its upper leg connected to the concavity in the roof to be drained and its lower leg leading to a point below the roof; means exposed to falling rain adapted to direct rain Water into the lower leg of the syphon to start th'e same; an enlargement with a discharge opening at the lower end of the lower leg; and means for yieldingly closing said discharge opening, said means adapted to be opened by a predetermined minimum amount of water in said enlargement.

3. Drainage apparatus for a concave roof, in-

r cluding: a syphon drain pipe with its upper leg connected to the concavity in the roof to be drained and its lower leg leading to a point below the roof; means exposed to falling rain adapted to direct rain water into the lower leg of the syphon to start the same; a swivel discharge pipe at the lower end of th'e lower leg; and means for yieldingly holding said discharge pipe in a substantially upright position, whereby a predetermined minimum amount of water will temporarily be trapped in the lower end of said lower leg and in said discharge pipe, the weight of Water in said discharge pipe exceeding said predetermined minimum amount, adapted to lower said discharge pipe to permit discharge of Water therethrough from said lower leg,

DONALD E. LARSON. 

